Last autumn, CNN released the results of a study it conducted into which countries foreign jihadists fighting in Syria were most likely to come from. Top of the list was Tunisia. According to the study, approximately 3,000 Tunisians had left their country to fight in Syria. That's revealing in light of the atrocity in Tunisia last week.
The top European country sending jihadists to Syria was Russia with 800, followed closely by France with 700.
The study also lists the countries with the biggest number of foreign jihadists in Syria as a percentage of the local Muslim population. Here's the worrying thing. Ireland is second on the list, very narrowly beaten by Finland.
The Muslim population of Ireland is still small at 43,000, according to the CNN study. (I have also seen figures putting it much higher than that).
Because the number of Muslims here is small, so is the number of fighters who have gone out from Ireland to Syria. Apparently, it is between 25 and 30, as of last September. That's still a disturbing number and represents about 0.07pc of Muslims in Ireland.
If a similar percentage of French Muslims had gone to fight in Syria, the number would be 3,290, not 700. The number of British Muslims fighting in Syria would be 2,000, not 500. In other words, there are four times as many Irish Muslims as British Muslims fighting in Syria, proportionately speaking.
What happens if and when those jihadists come home? What will they do? Will they simply slip quietly back into their communities or will they do something much more deadly, such as we have seen in countries like France?
These are the questions keeping our security services awake at night. Security expert Tom Clonan has said that Ireland is also used as "a transit hub and destination" for jihadists and those assisting jihadists because "Ireland does not have the type of security infrastructure and resources other jurisdictions have".
These are not Irish passport holders and therefore are in addition to the Irish passport holders who are fighting in Syria and elsewhere.
The three Irish killed on that beach in Tunisia last week by that jihadist were victims of Islamist extremism of the sort that has provoked intense debate in other parts of Europe about the place of Muslims in their societies.
It has given rise to political parties which want to restrict Muslim immigration in places like Denmark, where the recent general election saw the Danish People's Party win 21pc of the vote.
Denmark is often held up as the model society to Irish people by the Irish left.
It even seems to pip Sweden these days, but Denmark has a stronger political right than Ireland does, and of a less savoury type. One reason the right is on the rise in Denmark is because the left there for years has suppressed any proper debate about immigration.
Denmark has a Muslim population of 226,000, much higher than here, even though the overall population of Denmark is about the same as ours.
But anyone who raised any concerns at all about how this might have changed Danish society is instantly denounced as a racist, a bigot and an Islamophobe. The left throw around these sorts of accusations like snuff at a wake. As a tactic, it is often fantastically effective at ending public debate but clearly it has not suppressed public concerns as the rise of the Danish People's Party shows.
In this country, the growing number of Muslims here has sometimes impinged on public debate.
For example, should Muslim schoolgirls be allowed to wear headscarves? What about covering their faces entirely?
I take the view that they should be allowed to wear headscarves to school but not to cover their faces entirely, because that would act as a barrier between them and the rest of the class, including the teacher.
Should Muslims be allowed separate schools at all? Again, I'm a defender of the proposition that they should be, on the grounds that parents and not the State are the primary educators of their children and therefore schools should be responsive to the wishes of parents first and foremost.
The very strict attitude of Muslims towards the issue of blasphemy has also surfaced here sometimes.
Muslims are supportive of the blasphemy provision being retained in our Constitution and in statute law.
A Muslim academic hinted at legal proceedings against any newspaper which reprinted the admittedly pornographic depictions of the Prophet Mohammed that had been carried by Charlie Hebdo.
Personally, I support the removal of the blasphemy provision both from our Constitution and our statute law but not in a million years would I have printed depictions of Mohammed of the sort printed by Charlie Hebdo because they were so extreme.
I think a certain basic level of respect should be shown towards the views of others as a simple matter of courtesy. (It's different obviously if we are talking about the likes of Isil. They deserve no respect whatsoever).
However, despite the sort of matters just mentioned surfacing from time to time here, the Muslim presence in Ireland isn't a big public issue yet.
That will probably only happen if we see Islamism starting to manifest itself here in the way it has in countries like France.
We have to hope that the Irish jihadists who return to Ireland are well marshalled by our security forces.
First and foremost, however, that responsibility rests with the Muslim community itself. Voices condemning Islamist extremists from within the Muslim community need to be much louder and more insistent than they are at present.
We need to see Muslims demonstrate against jihadism in the same way they demonstrate against Israel.
They need to demonstrate against the extremists in their own ranks in order to show the wider community that they are deadly serious when they say that terrorism in the name of Islam besmirches the name of Islam.
Specifically, we need to see demonstrations against Isil. We never saw any to speak of when al-Qa'ida was the dominant jihadist group.
By combating the extremists in their midst, Muslims will ensure that no party like the Danish People's Party can ever arise in Ireland.